1. Field of the Invention
The present invention relates to a mechanical device used to grind down tree stumps.
2. Background of the Prior Art
The challenge of clearing land, scheduled for various types of commercial use, has been around since time immortal. Many methods and devices have been proposed for removing the stumps from the earth's surface in order to allow soil tillage, building construction, etc. Such devices include machines capable of grinding the tree stumps down below the surface level or completely out of the ground. Exemplary of such devices is U.S. Pat. No. 4,074,447 to Slivers et al., which includes a rotary cutting wheel powered by a driving means such as a combustion engine. Although designed for relatively safe operation, this and other examples of stump grinders found in the art are, nevertheless, subject to operator misuse, resulting in death or serious injury to the operator. Typical of such misuse occurs when the operator ventures out in front or the device and is injured by the rotating cutting wheel. Alternately, a flying piece of debris can strike the operator as he stands behind or beside the device while to operating the device.
Other problems associated with current stump grinders is their lack of ability to be moved from one stump grinding job to another. Many stump grinders are relocated from one grinding job to another by hooking the device to a truck or other tow vehicle and the vehicle moves the stump grinder. This method of relocation is slow and inefficient in requiring the operator to leave the controls of the stump grinder, climb into the tow vehicle, and actually move the stump grinder. Thereafter, the operator disembarks the tow vehicle, decouples the stump grinder and restarts the grinding process. This routine is very slow and inefficient as many stump grinding jobs involve hundreds or even thousands of stumps. The routine is physically demanding on the operator, resulting in manpower inefficiency and is also very cumbersome, especially in tight grinding jobs wherein the stump grinder must be maneuvered around trees, fences, buildings, and other obstacles.
Other stump grinders are designed for the operator to stand beside the machine. This type of stump grinder has a hydraulic motor on one of its wheels in order to propel the grinder from one stump to the next while the operator walks alongside or behind the device during relocation. Such grinders are also relatively difficult to relocate between stumps and they suffer from limited horsepower, further limiting their utility.
The above-mentioned stump grinders have at least three hydraulic cylinders, two pivot points and an extension arm in order to give the cutting wheel the ability to articulate up and down, laterally back and forth, and in and out. The result is that the stump grinders have at least 8 wear points, one at each end of the hydraulic cylinders, and one at each pivot point. The constant movement of these components along their various axis of articulation creates excessive wear of the components resulting in inefficient device performance and, potentially, danger to the operator resulting from device failure.
Therefore, there is a need in the art for a stump grinder that overcomes the problems associated with the current stump grinder devices. Such a stump grinder must have the capability to be quickly and efficiently relocated from one grinding job to another without undue physical demand on the operator. Relocation in tight stump grinding jobs must also be efficient. The device must provide maximum operator safety during operation. The device must have sufficient power to adequately perform on the largest grinding jobs. Such a device must have a design that reduces the number of wear points resulting in enhanced device reliability.